Two men have been arrested in the US state of Utah suspected of setting up potentially deadly booby traps on a popular canyon trail.

The devices consisted of a spiked boulder rigged to swing at head height and another designed to trip a passer-by into a bed of wooden stakes.

Police say it was lucky the trip wires were found by an eagled-eyed forestry officer on a routine patrol.

The hiking area is popular with families and college students.

The traps were set on the Big Springs trail in Provo Canyon about 50 miles (80km) south of Salt Lake City.

Benjamin Steven Rutkowski, 19, and Kai Matthew Christensen, 21, were arrested on Saturday and released on bail.

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The suspects were arrested after detectives were tipped off about comments on Facebook

They said the traps, built around a makeshift shelter, were intended for wildlife, but sceptical investigators are preparing charges of misdemeanour reckless endangerment.

"This is a shelter put together by people, visited by people - anything that would be impacted by their device would have to be humans," Utah County Sheriff's Sgt Spencer Cannon told the Associated Press news agency.

"It took some time to build these traps. They took rope, heavy-duty fishing line, and they intended what the traps were going to do."

The suspects were themselves snared after detectives were tipped off about comments on Facebook.

The medieval-style traps were spotted by a US Forest Service officer, James Schoeffler, who has military experience in detecting hazardous devices.

"A lot of people go up there after dark, as well," Sgt Cannon added. "We're very, very fortunate that it was Officer Schoeffler who found it."